1. Field
Embodiments relate to a conductive polymer compound and an organic photoelectric device including the same.
2. Description of the Related Art
A photoelectric device is a device for transforming photo energy to electrical energy, and conversely, for transforming electrical energy to photo-energy. The photoelectric device may be exemplified by an organic light emitting diode, a solar cell, a transistor, and so on.
Particularly, among these photoelectric devices, the organic light emitting device employing organic light emitting diodes (OLED) has recently drawn attention due to the increase in demand for flat panel displays (FPD).
In the field of photoelectric devices including the organic light emitting diode, researchers are studying the formation of a conductive polymer layer in order to improve efficiency of a photoelectric device by smoothly transferring charges generated in an electrode, that is, holes and electrons, to the photoelectric device.
An organic light emitting diode is an active light emitting display device taking advantage of a phenomenon in which electrons and holes are combined in an organic layer while emitting light when an electrical current flows to a fluorescent or phosphorescent organic compound thin film (hereinafter referred to as an organic layer). The organic light emitting diode does not use a single light emission layer as the organic layer but employs a multi-layer structure including a hole injection layer (HIL) using a conductive polymer, a light emission layer, and an electron injection layer (EIL) to improve efficiency and decrease a driving voltage.
The multi-layer structure can be simplified by making one layer perform a plurality of functions. One of the simplest OLED structures is a structure where an organic layer performing all functions including the function of a light emission layer is interposed between two electrodes.
However, to substantially increase luminance, an electron injection layer (EIL) or a hole injection layer should be introduced to an electrical light emitting assembly.
The literature discloses many organic compounds capable of transferring charges (which are holes and electrons) to be used by an electron injection layer (EIL) or a hole injection layer (HIL). As examples, European Patent Publication No. 387 715, U.S. Pat. No. 4,539,507, U.S. Pat. No. 4,720,432, and U.S. Pat. No. 4,769,292 disclose organic compounds and their usages.
Particularly, Baytron-P, which is commercially available in the market by the Bayer AG Company, is a representative organic compound capable of transferring charges and is used for soluble organic electro-luminescence (EL). Baytron-P is a kind of PEDOT (poly(3,4-ethylene dioxythiophene))-PSS (poly(4-styrene sulfonate)) aqueous solution.
PEDOT-PSS is widely used for fabrication of an organic light emitting diode. It is used to form a hole injection layer (HIL) by spin-coating it on an indium tin oxide (ITO) electrode. The PEDOT-PSS has a structure as shown in the following Chemical Formula A.

The PEDOT-PSS expressed in the above Chemical Formula A is a simple ion composite of a polyacid, which is poly(4-styrene sulfonate) (PSS), and a conductive polymer, which is poly(3,4-ethylenedioxythiophene) (PEDOT). It has a structure in which PEDOT is doped with a water-soluble polyacid.
However, when the hole injection layer (HIL) is formed using the PEDOT-PSS conductive polymer composition, the PSS is deteriorated and dedoped due to its property of absorbing moisture, or a part of the PSS may be decomposed through a reaction with electrons to thereby emit a material such as a sulfate. The emitted material may be diffused into a neighboring organic layer, such as a light emission layer. The diffusion of a material originating from the hole injection layer (HIL) into the light emission layer causes exciton quenching to thereby decrease the efficiency and life-span of the organic light emitting diode.
To overcome the drawbacks, U.S. Patent Publication No. 2005/0251597 and Korean Patent Publication No. 2006-0120378 disclose using a conductive polymer doped with an ionomer where both main chains and branch chains have substituted fluorine groups.

Such materials shown in the above Chemical Formula B have most of their carbon groups in the main chain and branch chain substituted with fluorine groups. Thus, the time that they are dispersed in water is short, and they form colloid-type particles. When a conductive polymer is prepared by using these materials, the particles agglomerate severely even with a minute increase in the length of the repeating unit of the conductive polymer. Also, when they are used for forming a thin film through a spin coating process, the generated thin film has poor uniformity.